Biochips are used particularly in the DNA chip and protein chip embodiments in biotechnology and genetic research. They are ascribed great potential in medical diagnostics, pharmacological and toxicological test procedures, and in the agricultural sector.
A biochip typically includes a two-dimensional array of regions having organic molecules (probes) that are immobilized on a surface and that can specifically react with chemical substances comprising a probe substance (targets). The objective here is the parallel detection of many interactions between probes and targets. When illuminated, photosensitive biochips exhibit a physical reaction that specifically depends on the interaction between probes and targets.
Detection of these interactions occurs, for example, by optical, autoradiographical, mass-spectroscopic, or electrical methods. In doing so, it is necessary to spatially address the various probes on the array. Optical (luminescence) and electrical detection methods, in particular, are known to date within the group of photosensitive biochips. For these chips, addressing can be achieved through spatially restricted optical excitation.
Laser scanners or confocal microscopes have been employed to date for optical excitation. The critical parameters here are uniformity and reproducibility across the entire spatial readout region of the chip. Because of these requirements, the original confocal construction by Minsky (U.S. Pat. No. 3,013,467) is often used as the basis for readout devices., for example as described in U.S. Pat. No. 5,631,734 and U.S. Pat. No. 5,578,832. It consists of an xyz translation table that can be moved below a confocal microscope. In JP11094747, a rotating table is used instead of a translation table. In these methods, the biochip must withstand the occurring acceleration of the table. This ultimately determines the time span in which the chip can be read out. For example, the readout process for a 22×60 mm scan region with a resolution of 10 μm takes about half an hour.
Other optical readout systems, such as that described in WO09947964A1, are based on movable optical components, which make the construction expensive and/or susceptible to interference.
A special readout system for photosensitive biochips with electrical readout is not known to date.
Disadvantages of all known scanning systems are that they are mechanically vulnerable, relatively large, and expensive.